Auto-document feeder and document feeding method

ABSTRACT

An auto-document feeder includes: a document placing section on which an original document is placed; a sheet detection sensor configured to detect the original document, length in a feeding direction of the original document being first length larger than second length; a length detection sensor configured to detect the length of the original document while the original document is fed; a first feeding path for feeding the original document to a reading section for reading an image of the original document; a second feeding path for feeding the original document to the reading section, the second feeding path being different from the first feeding path; a switching section configured to selectively switch the first feeding path and the second feeding path; and a control section configured to divert, with the switching section, the original document to the first feeding path if the sheet detection sensor detects the original document.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from:U.S. provisional application 61/393,336, filed on Oct. 14, 2010 andJapanese Patent Application No. 2011-201386 field on Sep. 15, 2011; theentire contents all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an auto-document feederand a document feeding method for feeding an original document to animage reading apparatus.

BACKGROUND

As an image reading apparatus including an auto-document feeder used inan image forming apparatus or the like, there is known an image readingapparatus that includes two sheet feeding paths. In reading pluraloriginal documents, the image reading apparatus diverts the originaldocuments to be read to the two sheet feeding paths to improveproductivity of the reading.

An image reading apparatus including an auto-document feeder performsreading of an original document after detecting the size of the originaldocument with a first sensor on a tray on which the original document isplaced and a second sensor in a sheet feeding path.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic diagram of an image readingapparatus according to a first embodiment;

FIG. 2 is a block diagram of a control system for an auto-documentfeeder according to the first embodiment;

FIG. 3 is a flowchart for explaining sheet feeding by the auto-documentfeeder according to the first embodiment;

FIG. 4 is a flowchart for explaining the sheet feeding by the autodocument feeder according to the first embodiment;

FIG. 5 is a flowchart for explaining normal feeding of an originaldocument in the auto-document feeder according to the first embodiment;and

FIG. 6 is a flowchart for explaining sheet feeding by an auto-documentfeeder according to a second embodiment.

DETAILED DESCRIPTION

According to an embodiment, an auto-document feeder includes a documentplacing section on which an original document is placed. A sheetdetection sensor configured to detect the original document placed onthe document placing section, length in a feeding direction of theoriginal document being first length larger than second length. A lengthdetection sensor configured to detect the length in the feedingdirection of the original document while the original document is fed. Afirst feeding path for feeding the original document placed on thedocument placing section to a reading section for reading an image ofthe original document, a distance from the length detection sensor tothe reading section in the first feeding path being larger than thefirst length. A second feeding path for feeding the original documentplaced on the document placing section to the reading section, thesecond feeding path being different from the first feeding path. Aswitching section configured to selectively switch the first feedingpath and the second feeding path. A control section configured todivert, with the switching section, the original document to the firstfeeding path if the sheet detection sensor detects the originaldocument. An original document contains one or more sheets having thesame or different sized sheets.

Embodiments of the present invention are explained below with referenceto the accompanying drawings.

First Embodiment

A first embodiment is explained with reference to FIGS. 1 to 5.

FIG. 1 is a cross-sectional schematic sectional view of an image readingapparatus according to the first embodiment.

An image reading apparatus 100 includes a scanner 110, which is an imagereading section, and an ADF (auto-document feeder) 10 configured to feedan original document G to the scanner 110. The scanner 110 includes aREAD document glass 110 a, a platen glass 110 b of a document placingtable, and an optical mechanism 110 c. The optical mechanism 110 coptically reads an image of the original document G traveling on orpassing over the READ document glass 110 a. Alternatively, the opticalmechanism 110 c is moved by a not-shown driving means along the platenglass 110 b in an arrow A direction (see FIG. 1) and optically reads animage of the original document G placed on the platen glass 110 b. Thescanner 110 includes a photosensor 110 d, such as a CCD (Charge CoupledDevice), CMOS(Complementary Metal Oxide Semiconductor), CIS(ContactImage Sensor), or the like, configured to photoelectrically convert alight signal from the optical mechanism 110 c into an electric signal.

The auto-document feeder 10 includes a document tray 11, which is adocument placing section, a pickup roller 12 configured to pick up theoriginal document G from the document tray 11, a separating and feedingroller 13 configured to prevent the original document G from beingdoubly fed (that is, to feed one original document at a time, not feedmultiple documents simultaneously), and a registration roller 14configured to align the leading end of the original document G picked upfrom the document tray 11 and fed.

The document tray 11 includes a sheet detection sensor 21. The sheetdetection sensor 21 is provided in a position on the document tray 11where, if an original document, the length in a feeding direction ofwhich is a first length, is placed on the document tray 11, the sheetdetection sensor 21 detects the original document but, in the case of anoriginal document, the length in the sheet feeding direction of which issecond length smaller than the first length, the sheet detection sensor21 does not detect the original document. For instance, the first lengthis maximum length in a feeding direction of an original document thatthe auto-document feeder 10 can feed.

For example, as the original document, the length in the sheet feedingdirection of which is the first length, an original document of the A3size paper is conceivable. As the original document, the length in thesheet feeding direction of which is the second length, an originaldocument of the A4 size paper is conceivable. Of course, otherdifferently sized papers are possible.

The auto-document feeder 10 includes two feeding paths: an OUT path 16,which is a first feeding path spanning from the registration roller 14to the scanner 110, and an IN path 17, which is a second feeding pathspanning from the registration roller 14 to the scanner 110.

In a document feeding path before branching from the document tray 11 tothe OUT path 16 and the IN path 17, a length detection sensor 22configured to detect the length in a feeding direction of the originaldocument G and a width detection sensor 23 configured to detect thewidth, which is the length in a direction orthogonal to the feedingdirection of the original document G, are provided. The length detectionsensor 22 detects the length of the original document G in the feedingdirection according to time until the trailing end of the originaldocument G is detected after the leading end of the original document Gis detected.

In the OUT path 16, a distance from the length detection sensor 22 tothe READ document glass 110 a, which is a reading position for theoriginal document G, is larger than the first length of the originaldocument. Since the length from the length detection sensor 22 to theREAD document glass 110 a is larger than the first length, the length inthe feeding direction of the original document G can be detected whilethe original document, the length in the sheet feeding direction ofwhich is the first length is fed through the OUT path 16. The IN path 17is different from and typically shorter than the OUT path 16. The lengthfrom the length detection sensor 22 to the READ document glass 110 a isdifferent from and typically smaller than the first length.

The auto-document feeder 10 includes a pre-reading roller 50 configuredto feed the original document G passed through the OUT path 16 or the INpath 17 to the READ document glass 110 a of the scanner 110, apost-reading roller 51 configured to discharge the original document Gfrom the READ document glass 110 a, a pre-paper discharge roller 52, apaper discharge roller 53, and a paper discharge tray 56. A CIS (ContactImage Sensor) 60 is provided between the post-reading roller 51 and thepre-paper discharge roller 52. The CIS 60 can be provided, for example,in a feeding path reaching from the pre-paper discharge roller 52 to thepaper discharge roller 53.

On the READ document glass 110 a, the optical mechanism 110 c reads animage on a front surface, which is a first surface, of the originaldocument G traveling on the glass surface. The CIS 60 can read an imageon a rear surface, which is a second surface, of the original document Gtraveling to pass the READ document glass 110 a.

An empty sensor 70 configured to detect presence or absence of theoriginal document G is arranged above the document tray 11 on a sidewhere the original document G is acquired. A registration sensor 71configured to detect that the original document G reaches theregistration roller 14 is arranged between the separating and feedingroller 13 and the registration roller 14. In the OUT path 16, theregistration roller 14 and a paper timing sensor OUT 72, which is afirst timing sensor, configured to detect driving timing for anintermediate OUT roller 18 are arranged. In the IN path 17, theregistration roller 14 and a paper timing sensor IN 73, which is asecond timing sensor, configured to detect driving timing for anintermediate IN roller 28 are arranged.

A pre-reading sensor 76 is arranged between the pre-reading roller 50and the READ document glass 110 a. A reading sensor 77 is arrangedbetween the post-reading roller 51 and the re-discharge roller 52. Apaper discharge sensor 78 is arranged between the pre-paper dischargeroller 52 and the paper discharge roller 53.

A paper feeding motor 80 drives to rotate the pickup roller 12 and theseparating and feeding roller 13. When the original document G on thedocument tray 11 is acquired, a pickup solenoid 81 swings the pickuproller 12. A registration motor (RGT motor) 82 drives to rotate theregistration roller 14. A gate solenoid 83 operates to switch a gate 40,which is a switching section for the feeding path. On one hand, if thegate solenoid 83 is turned off, the gate 40 pivots in an arrow xdirection and diverts the original document G to the OUT path 16. On theother hand, if the gate solenoid 83 is turned on, the gate 40 pivots inan arrow y direction and diverts the original document G to the IN path17.

An intermediate OUT motor 84 drives to rotate the intermediate OUTroller 18 to rotate. An intermediate IN motor 86 drives to rotate theintermediate IN roller 28 to rotate. A READ motor 87 drives thepre-reading roller 50 to rotate, the post-reading roller 51 to rotate,and the pre-paper discharge roller 52 to rotate. A paper discharge motor88 drives the paper discharge roller 53 to rotate.

A block diagram of a control system 120 mainly for the auto-documentfeeder 10 is shown in FIG. 2. A main body control section 121 configuredto control an entire image forming apparatus including the image readingapparatus 100 is connected to the photosensor 110 d of the scanner 110and the CIS 60. The main body control section 121 controls a CPU 130,which is a control section, of the auto-document feeder 10 via an inputand output interface 122. The empty sensor 70, the registration sensor71, the paper timing sensor OUT 72, the paper timing sensor IN 73, thepre-reading sensor 76, the reading sensor 77, and the paper dischargesensor 78 are connected to an input side of the CPU 130. Further, thesheet detection sensor 21, the sheet length detection sensor 22, and thewidth detection sensor 23 are connected to the CPU 130.

The pickup solenoid 81, the paper feeding motor 80, the RGT motor 82,the gate solenoid 83, the intermediate OUT motor 84, the intermediate INmotor 86, the READ motor 87, and the paper discharge motor 88 areconnected to an output side of the CPU 130.

A sheet feeding method by the auto-document feeder according to thisembodiment is explained with reference to the flowcharts of FIGS. 3 and4.

After a power supply is turned on or during return from a standby state,the CPU 130 confirms that the auto-document feeder 10 is closed (Act 1).If the CPU 130 confirms that the auto-document feeder 10 is closed (Noin Act 1), the CPU 130 detects outputs of all the sensors and confirmsthat a paper jam does not exist in the auto-document feeder 10 (Act 2).If a paper jam is detected according to an output of any one of thesensors (No in Act 2), the CPU 130 notifies, for example, the main bodycontrol section 121 of the existence of a paper jam. The control section121 performs display of the paper jam on a display (not shown) of apublicly-known operation panel included in the image forming apparatusand urges a user to perform a jam treatment. On the other hand, if apaper jam is not detected from outputs of all the sensors (Yes in Act2), the CPU 130 determines whether the original document G is present onthe document tray 11.

When the original document G is placed on the document tray 11, theempty sensor 70 is turned on. Therefore, the CPU 130 detects whether theempty sensor 70 is on (Act 3). If the empty sensor 70 is not on (No inAct 3), the CPU 130 returns to Act 1 and determines whether the ADF 10is closed. On the other hand, if the empty sensor 70 is on (Yes in Act3), the CPU 130 transmits a document ON signal to the main body controlsection 121 and determines whether a paper feeding request signal isreceived from the main body control section 121 (Act 4).

If the paper feeding request signal is received from the main bodycontrol section 121 (Yes in Act 4), the CPU 130 determines according toan output of the sheet detection sensor 21 whether the original documentG is detected (Act 5). If the paper feeding request signal is notreceived (No in Act 4), the auto-document feeder 10 changes to thestandby state.

If the sheet detection sensor 21 detects the original document G on thedocument tray 11, this means that the length in the feeding direction ofthe original document G is the first length.

If the CPU 130 determines that the sheet detection sensor 21 detects theoriginal document G (Yes in Act 5), the CPU 130 turns off the gatesolenoid 83 and moves the gate 40 to feed the original document G to theOUT path 16. Thereafter, the CPU 130 turns on the pickup solenoid 81,turns on the paper feeding motor 80, and rotates the pickup roller 12and the separating and feeding roller 13 to start an operation forfeeding the original document G to the OUT path 16 (Act 6).

According to the start of the feeding of the original document G to theOUT path 16, the CPU 130 decides a sheet size of the original document Gaccording to detection results of the length detection sensor 22 and thewidth detection sensor 23 provided in the feeding path of the OUT path16 (Act 7).

The CPU 130 drives the RGT motor 82 and the intermediate OUT motor 84 tofeed the original document G, the sheet size of which is decided in Act7, to the READ document glass 110 a, which is a reading section, of thescanner 110 (Act 8).

Subsequently, the CPU 130 instructs reading of the original document Gfed to the READ document glass 110 a (Act 9).

Thereafter, the CPU 130 drives the paper discharge motor 88, dischargesthe original document G to the paper discharge tray 56, and ends theprocessing (Act 10).

If the CPU 130 does not determine in Act 5 that the sheet detectionsensor 21 detects the original document G (No in Act 5), the originaldocument G is normally fed. In this case, the length in the feedingdirection of the original document G on the document tray 11 is thesecond length, which is smaller than the first length.

In the normal feeding in this embodiment, the original document G isalternately fed to the IN path and the OUT path. A flow for alternatelydiverting the original document G to the IN path and the OUT path in thenormal feeding is explained with reference to a flowchart of FIG. 5.

If the sheet detection sensor 21 does not detect the original documentG, when the normal feeding in the auto-document feeder 10 is started,the CPU 130 feeds the original document G to the IN path 17 or the OUTpath 16 (Act 16). In this embodiment, a first original document G1 isfed to the IN path 17. In this case, the CPU 130 turns on the gatesolenoid 83 and moves the gate 40 to feed the first original document G1to the IN path 17. Thereafter, the CPU 130 drives the paper feedingmotor 80 and starts the feeding of the first original document G1 to theIN path 17.

Subsequently, the CPU 130 determines whether the trailing end of thefirst original document G1 passes through the registration sensor 71 andthe registration sensor 71 changes from ON to OFF (Act 17). If the CPU130 determines that the trailing end of the first original document G1passes through the registration sensor 71 (Yes in Act 17), the CPU 130determines presence or absence of a second original document G2according to a detection result of the empty sensor 70 (Act 18).

If the CPU 130 determines that the second original document G2 ispresent (Yes in Act 18), the CPU 130 feeds the second original documentG2 to the IN path 17 or the OUT path 16 different from the feeding pathto which the first original document G1 is fed (Act 19). In thisembodiment, since the first original document G1 is fed to the IN path17, the CPU 130 feeds the second original document G2 to the OUT path16. In this case, the CPU 130 turns off the gate solenoid 83 and movesthe gate 40 to feed the second original document G2 to the OUT path 16.Thereafter, the CPU 130 drives the paper feeding motor 80 and starts thefeeding of the second original document G2 to the OUT path 16.

The processing for diverting the first original document G1 to the INpath 17 and diverting the second original document G2 to the OUT path 16as explained above to divert plural original documents Gn to the twofeeding paths of the IN path 17 and the OUT path 16 ends. Third andsubsequent original documents are diverted to the IN path 17 and the OUTpath 16 in the same manner considering an immediately preceding originaldocument as the first original document in the flowchart of FIG. 5.

As explained above, in the normal feeding, since original documents arealternately diverted to the IN path 17 and the OUT path 16, before theimmediately preceding original document is discharged from the feedingpath feeding of the next original document can be started. Therefore, itis possible to efficiently feed the original documents compared withfeeding plural original documents using only one feeding path.

According to the embodiment, since a sheet size of an original documentis detected even if the original document is an original document whichis long in the sheet feeding direction, it is unnecessary to feed theoriginal document to the reading section again after once causing theoriginal document to pass the reading section. If the original documentis an original document which is short in the sheet feeding direction,since the original document is diverted to the first feeding path andthe second feeding path, it is possible to keep high productivity inreading of the original document.

Second Embodiment

A second embodiment is explained with reference to FIG. 6.

In the following explanation, components that are the same or similar asthose in the first embodiment are denoted by the same reference numeralsfor brevity and signs and only characteristic sections of a secondembodiment are explained. In this embodiment, processing performed whena user inputs in advance a mixed document mode for performing reading ofplural original documents having various mixed sheet sizes is explained.

FIG. 6 is a flowchart for explaining a sheet feeding method for anauto-document feeder according to this embodiment.

Acts 1 to 3 are the same or similar as those in the flowchart of FIG. 3in the first embodiment. If the empty sensor 70 is on in Act 3 (Yes inAct 3), the CPU 130 determines whether the mixed document mode is inputfrom the main body control section 121 (Act 21). The instruction of themixed document mode is performed by the user from, for example, anoperation panel of the image forming apparatus. The main body controlsection 121 receives the input of the mixed document mode. Thereafter,the main body control section 121 transmits the input of the mixeddocument mode to the CPU 130 of the auto-document feeder 10.

If the CPU 130 receives the input of the mixed document mode in Act 21(Yes in Act 21), the CPU 130 sets the mixed document mode (Act 22).

When the mixed document mode is set in Act 22, as in Act 4 andsubsequent acts in FIG. 3, the CPU 130 controls a feeding method for theoriginal document G according to a detection result of the sheetdetection sensor 21 on the document tray 11. Specifically, if the sheetdetection sensor 21 detects the original document G (if the originaldocument G has the first length), the original document G is diverted tothe OUT path 16. On the other hand, if the sheet detection sensor 21does not detect the original document G (if the original document G hasthe second length), as explained above, for example, if there are two ormore original documents G, the CPU 130 diverts first and second originaldocuments respectively to the IN path 17 and the OUT path 16 or viceversa referring to the feeding path of the immediately precedingoriginal document.

If the CPU 130 does not receive the input of the mixed document mode inAct 21 (No in Act 21), the original document G is normally fed. Thenormal feeding is the feeding method explained with reference to theflow chart of FIG. 5 in the first embodiment.

As in this embodiment, the feeding path is determined using a detectionresult of the sheet detection sensor 21 on the document tray 11 only ifthe mixed document mode is input from the user. Therefore, during themixed document mode in which the original documents G having varioussheet sizes are mixed, it is possible to select optimum feeding pathsfor the respective original documents. In the case of feeding of theoriginal document G having a fixed sheet size not in the mixed documentmode, it is possible to efficiently feed the original document G byimmediately performing the normal feeding.

The several embodiments are explained above. However, these embodimentsare presented as examples and are not intended to limit the scope of theinvention. These new embodiments can be carried out in other variousforms. Various omissions, substitutions, and changes of the embodimentsare possible without departing from the spirit of the invention. Theseembodiments and modifications thereof are included in the scope and thegist of the invention and are included in the inventions described inclaims and the scope of equivalents of the inventions.

1. An auto-document feeder comprising: a document placing section onwhich an original document is placed; a sheet detection sensorconfigured to detect the original document placed on the documentplacing section, a length in a feeding direction of the originaldocument being a first length larger thap a second length; a lengthdetection sensor configured to detect the length in the feedingdirection of the original document while the original document is fed; afirst feeding path for feeding the original document placed on thedocument placing section to a reading section for reading an image ofthe original document, a distance from the length detection sensor tothe reading section in the first feeding path being larger than thefirst length; a second feeding path for feeding a different sheet of theoriginal document placed on the document placing section to the readingsection, the second feeding path being different from the first feedingpath; a switching section configured to selectively switch between thefirst feeding path and the second feeding path; and a control sectionconfigured to divert, with the switching section, the original documentto the first feeding path if the sheet detection sensor detects theoriginal document.
 2. The auto-document feeder according to claim 1,wherein the first length is a maximum length in the feeding direction ofthe original document that the auto-document feeder can feed.
 3. Theauto-document feeder according to claim 1, wherein, in the secondfeeding path, a distance from the length detection sensor to the readingsection is smaller than the first length.
 4. The auto-document feederaccording to any one of claim 1, wherein, if the sheet detection sensordoes not detect an original document having the second length smallerthan the first length placed on the document placing section, thecontrol section alternately diverts, with the switching section, theoriginal document to the first feeding path and the second feeding path.5. The auto-document feeder according to claim 1, wherein, if pluraldocuments are placed on the document placing section, the controlsection receives input of a mixed document mode indicating that anoriginal document, a length in the feeding direction of which is thefirst length or the second length smaller than the first length, isincluded and, if the input of the mixed document mode is received,diverts the original documents to the first feeding path or the secondfeeding path on the basis of a detection result by the sheet detectionsensor.
 6. The auto-document feeder according to claim 5, wherein, ifthe sheet detection sensor does not detect the original document havingthe second length placed on the document placing section, the controlsection alternatively diverts, with the switching section, the originaldocument having the second length to the first feeding path or thesecond feeding path.
 7. A document feeding method for an auto-documentfeeder including: a sheet detection sensor provided in a documentplacing section; plural feeding paths for feeding an original documentplaced on the document placing section to an image reading section,lengths of the plural feeding paths at least from a length detectionsensor to the reading section being different from one another; and aswitching section configured to selectively switch the plural feedingpaths, the method comprising: determining whether an original document,the original document having a length in a feeding direction of which isfirst length larger than second length, is detected by the sheetdetection sensor; and diverting, if the original document placed on thedocument placing section is detected by the sheet detection sensor, withthe switching section, the original document to a first feeding path, alength of which is larger than the first length of the originaldocument, among the plural feeding paths.
 8. The method according toclaim 7, wherein the first length is a maximum length in the feedingdirection of the original document that the auto-document feeder canfeed.
 9. The method according to claim 7, further comprising receiving,in reading plural original documents, input of a mixed document modeindicating that an original document, length in the feeding direction ofwhich is the first length or the second length smaller than the firstlength, is included and, if the input of the mixed document mode isreceived, diverting, with the switching section, at least the originaldocument having the first length to the first feeding path on the basisof a detection result by the sheet detection sensor.
 10. The methodaccording to claim 8, wherein the auto-document feeder includes a secondfeeding path, and the method further comprises alternately diverting,with the switching section, the original document to the first feedingpath and the second feeding path if the sheet detection sensor does notdetect an original document having the second length.